Surface-modified nanoparticles via thermal and Cu(<scp>i</scp>)-mediated “click” chemistry: Generation of luminescent CdSe nanoparticles with polar ligands guiding supramolecular recognition
作者:Wolfgang H. Binder、Robert Sachsenhofer、Christoph J. Straif、Ronald Zirbs
DOI:10.1039/b618510j
日期:——
A new, simple and highly versatile method for the surface modification of luminescent cadmium selenide nanoparticles (CdSe NPs) based on 1,3-dipolar cycloaddition reactions is described. Uniform, trioctylphosphine oxide (TOPO)-covered CdSe NPs were prepared and subjected to two ligand-exchange reactions: first, ligand exchange was accomplished with pyridine, fully removing the TOPO ligand from the CdSe surface. In a second step, either 1-[(3-azidopropyl)octylphosphinoyl]octane or hex-5-ynoic acid 3-(dioctylphosphinoyl)propyl ester were added, attaching an azido or an acetylene moiety to the NP surface. Further thermal or Cu(I)-mediated 1,3-dipolar cycloaddition reactions on the residual azido/acetylene moieties with a variety of acetylenes/azides furnished the modified CdSe NPs with supramolecular receptors (i.e. barbituric acid, thymine, oligoethyleneglycol) on their surface. Photoluminescence measurements reveal a â¼50% residual quantum yield (relative to TOPO-covered CdSe NPs) after ligand modification, thus presenting an efficient pathway towards luminescent, surface modified CdSe NPs. The presence of the different functional groups was proven by 1H-NMR, 31P-NMR spectroscopy and by use of a nanoparticle-bound spiropyran dye and subsequent fluorescence quenching experiments. In order to further exploit the ligands on the CdSe NP surfaces, supramolecular recognition via binding to self-assembled monolayers (SAMs) presenting the matching receptor was investigated, leading to dense layers of CdSe NPs on planar surfaces as verified by AFM measurements. The concept offers a simple method for guiding the binding and recognition of luminescent CdSe NPs and related NPs onto surfaces.
本文描述了一种基于1,3-偶极环加成反应的新型、简单且高度通用的发光硒化镉纳米粒子(CdSe NPs)表面改性方法。制备了均匀的三辛基氧化膦(TOPO)覆盖的CdSe NPs,并使其发生两次配体交换反应:首先,用吡啶完成配体交换,完全去除CdSe表面上的TOPO配体。第二步,加入1-[(3-叠氮丙基)辛基膦酰]辛烷或己-5-炔酸3-(二辛基膦酰)丙酯,将叠氮或乙炔部分连接到NP表面。在残留的叠氮/乙炔部分上进一步发生热或Cu(I)介导的1,3-偶极环加成反应,与各种乙炔/叠氮反应,使改性CdSe NPs表面具有超分子受体(即巴比妥酸、胸腺嘧啶、寡乙二醇)。光致发光测量显示,配体改性后残留量子产率为50%以下(相对于TOPO覆盖的CdSe NPs),从而为发光、表面改性的CdSe NPs提供了有效途径。1H-NMR、31P-NMR光谱以及纳米粒子结合螺吡喃染料和随后的荧光淬灭实验证明了不同